1. OBJECTIVES/METHODS: Bleed vaccinees annually; test serum for rabies- neutralizing antibody by the Rapid Fluorescent Focus Inhibition Test (RFFIT); boost those with <1.0 International Unit rabies-neutralizing antibody/ml serum with HDCS Rabies Vaccine (Institut Merieux). 2. RESULTS: Distribution of human serum quantified for rabies- neutralizing antibody in IU/ml: Employing Agency Number of People Number of RFFIT (serum source) Sampled Tests CBER-FDA 10 20 NIH 80 160 TOTAL HUMAN SERUM TESTS 90 180